Margaret Tyzack
as Elena
Keir Dullea
as Dr. Dave Bowman
Gary Lockwood
as Dr. Frank Poole
William Sylvester
as Dr. Haywood R. Floyd
Daniel Richter
as Moonwatcher
Leonard Rossiter
as Dr. Andrei Smyslov
Douglas Rain
as HAL 9000
Robert Beatty
as Dr. Ralph Halvorsen